Several enumeration forms were used to collect the information for the 1960 Census of Population. A few days before the census date, the Post Office Department delivered an Advance Census Report (ACR) to households on postal delivery routes. This ACR also went to small institutions, such as nursing homes. This form contained questions which were to be answered for every person and every housing unit. Household members were requested to fill the ACR and have it ready for the enumerator. The census enumerator recorded this information on a form specially designed for electronic data processing by FOSDIC (Film Optical Sensing Device for Input to Computer). The information was either transcribed from the ACR to the complete- count FOSDIC schedule or entered on this schedule during direct interview.
In the densely populated areas, the enumerator left a Household Questionnaire to be completed by each household (or person) in the sample and mailed to the local census office. The population and housing information was transcribed from the Household Questionnaire to a sample FOSDIC schedule. When the Household Questionnaire was not returned or was returned without having been completed, the enumerator collected the missing information by personal visit or by telephone and entered it directly on the sample FOSDIC schedule. In the remaining areas, when the enumerator picked up the ACR, he obtained all the information by direct interview and recorded it directly on the sample FOSDIC schedule.

Soon after the enumerator started work, his schedules were examined in a formal field review. This operation was designed to assure at an early stage of the work that the enumerator was performing his duties properly and had corrected any errors he had made.

Special enumeration arrangements were made for many institutions. In General, the enumerators were expected to obtain information from office records and institution officials only for inmates in the following types of institutions: Federal and State prisons; homes for neglected and dependent children; residential treatment centers; homes or schools for the crippled, blind, or deaf; homes or schools for the mentally deficient or handicapped; mental hospitals; hospitals for the chronically ill; and tuberculosis hospitals. They were expected to obtain information by direct interview where possible in such institutions as: Public and private schools for juvenile delinquents; local workhouses; and homes for the aged, with or without nursing care. When an inmate could not be interviewed directly, as was usually the case in General hospitals and homes for unwed mothers, Individual census report forms were distributed for the inmates to fill out and return. Local jails, detention centers, and reception and diagnostic centers were visited on "M night" (April 1, 1960), and the inmates were generally interviewed directly, with recourse to office records where necessary. All the data were trans- scribed to FOSDIC forms.

More detailed descriptions of the 1960 Census procedures in the collection and processing of the data are given in reports entitled United States Censuses of Population and Housing, 1960: Principal Data Collection Forms and Procedures, 1961; and Processing the Data, 1962, U.S. Government Printing Office, Washington 25, D.C.

After the FOSDIC forms had been checked for completeness in the field, they were sent to a central processing office for Manual Editing and Coding and for microfilming. Except where some special problems arose, there was no manual coding of the FOSDIC forms for complete-count data. On the sample forms, the manual operation was limited to those items where coding required the reading of written entries and therefore could not be done effectively by machine. The coding clerks converted the written entries to codes by marking the appropriate circles on the FOSDIC schedules and at the same time were able to correct obviously wrong entries and sometimes supply missing information.

After the enumerators and coders recorded the information by marking the appropriate circles, the schedules were microfilmed. The information on the microfilm was then read by FOSDIC, which converted the markings to signals on magnetic tape. The tape, in turn, was processed in an electronic computer, which was used extensively to edit and tabulate the data and to produce the publication tables.

For a majority of items, nonresponses and inconsistencies were eliminated by using the computer to assign entries and correct inconsistencies. In General, few assignments or corrections were required, although the relative frequency varied by subject and by enumerator and was generally higher for Inmates than for other persons.
In a few cases involving small institutions, the electronic computer was unable to read the FOSDIC marks for type of Institution; In such cases, the computer used an allocation procedure that was based on the age of the first inmate enumerated in that institution. Hence, it is likely that in these few cases certain inconsistencies between the characteristics of inmates and Type of Institution will arise.

The assignment of an acceptable entry by machine was based on related information reported for the person or on information reported for a similar person in the immediate neighborhood. For example, in the assignment of age in the complete-count tabulations, the computer stored reported ages of persons by sex, color or race, household relationship, and marital status; each stored age was retained in the computer only until a succeeding person having the same characteristics and having age reported was processed through the computer; this stored age was assigned to the next person whose age was unknown and who otherwise had the same characteristics. This procedure insured that the distribution of ages assigned by the computer for persons of a given set of characteristics would correspond closely to the reported age distribution of such persons as obtained in the current census.

The relative extent of the allocations for non- response or for inconsistency in specified characteristics of inmates is shown in appendix table A-1. For each characteristic shown, the allocations relate only to those made by the electronic computer. Excluded are assignments made in the field review of schedules, in the Manual Editing and Coding operation, or in the manual repair of schedules where the computer had made more than the tolerable number of assignments during the initial processing.

For most characteristics of inmates, any number of computer assignments was tolerated. The only exceptions involved Type of Institution and selected sample characteristics; i.e., education, Year Moved into Institution, and 1959 income and work experience. (Data on income are not shown in the present report.) Type of Institution was manually assigned for rejected enumeration districts with non-reports on Type of Institution for 25 or more inmates by reference to independent lists. Education, Year Moved into Institution, and 1959 income and work experience were manually assigned for a subsample of inmates in enumeration districts containing 25 or more non-reports in these characteristics. The schedules were then returned to the electronic computer for assignments for other inmates not in the subsample. The manual assignment of selected sample characteristics for a subsample was intended to improve the quality of the computer assignments for other inmates. The manual assignments were based on distributions of values obtained from acceptable data for other institutions of similar type.

Human and mechanical errors occur in any mass statistical operation such as a decennial census. Such errors include failure to obtain required information from respondents, obtaining inconsistent information, recording information in the wrong place or incorrectly, or otherwise producing inconsistencies between entries on interrelated items on the field documents. Sampling biases occur because some of the enumerators fall to follow the sampling instructions. Clerical coding and editing errors occur, as well as errors in the Electronic Processing operation.

Careful efforts are made in every census to keep the errors in each step at an acceptably low level. Review of the enumerator's work, verification of manual coding and Editing, checking of tabulated figures, and Ratio Estimation of sample data to control totals from the complete count reduce the effects of the errors in the census data.
Very minor differences between tables in this report or between corresponding data in this report and chapters C and D of Volume I, Characteristics of the Population, result from imperfections in the electronic equipment. No attempt has been made to reconcile these minor discrepancies.

Some innovations in the 1960 Censuses reduced errors in processing and others produced a more consistent quality of Editing. The elimination of the card-punching operation removed one important source of error. The extensive use of electronic equipment insured a more uniform and more flexible edit than could have been accomplished manually or by less intricate mechanical equipment. It is believed that the use of electronic equipment in the 1960 Censuses has improved the quality of the Editing compared with that of earlier censuses but, at the same time, it has introduced an element of difference in the statistics.

A group of reports designated "Evaluation and Research Series" will deal with the methods, results, and interpretation of a group of evaluation and research studies of the 1960 Censuses of Population and Housing. A report entitled The Post-Enumeration Survey: 1950, Technical Paper No.4, presents evaluative material on the 1950 Census.